Device for iontophoretic application of fluoride on tooth

Abstract

In order to electrically apply fluoride by means of iontophoresis on a tooth an intermittent direct current is made to flow through the tooth. More particularly, the intermittent direct current has a waveform whose leading edge immediately rises to a peak and which decreases exponentially in time. As a result electrochemical polarization may be avoided and the ratio of the current conduction time to the repetition period may be increased so that the uptake efficiency of fluoride by the tooth may be considerably improved in a smooth manner without the need of impressing an excessive current on the tooth. Therefore adverse effects on nerve systems may be avoided, a patient under treatment feels no pain and no unpleasant stimulus, and the tooth's substance may be so improved as to be free from dental caries or decay.

What is claimed is: 
     
       1. A device for injecting fluoride ions into a tooth comprising means including an electrolyte containing fluoride and an electrode in electrical contact with said electrolyte, said electrolyte being adapted for contact with a body;   a positive terminal adapted for electrical contact with said body;   a negative terminal in electrical contact with said electrode; and   a current conduction means for permitting an intermittent direct current to flow between said positive and negative terminals, said current conduction means generating an intermittent direct current having a waveform which reaches a maximum level immediately after the current conduction is started and thereafter decays in time.   
     
     
       2. A device as set forth in claim 1 wherein said waveform of said intermittent direct current decreases exponentially in time. 
     
     
       3. A device as set forth in claim 2 wherein the ratio of the conduction time to the repetitive period of said intermittent direct current is between 1/10 and 1/2. 
     
     
       4. A device as set forth in claim 3 wherein said intermittent direct current has a frequency between 5 Hz and 1 KHz and a magnitude between 50 μA and 500 μA. 
     
     
       5. A device as set forth in claim 1 wherein the ratio of the conduction time to the repetitive period of said intermittent direct current is between 1/10 and 1/2. 
     
     
       6. A device as set forth in claim 5 wherein said intermittent direct current has a frequency between 5 Hz and 1 KHz and a magnitude between 50 μA and 500 μA. 
     
     
       7. A device as set forth in claim 1, wherein said current conduction means comprises: power supply circuit means for generating a stabilized direct current output, said power supply circuit means including switching means interconnected between a power supply and a load.   timer circuit means for turning off said switching means a predetermined time after said power supply circuit means has started to generate said directed current output, and   waveshaping circuit means actuable in response to said direct current output from said power supply circuit means for oscillating and thereby generating an intermittent direct current, said waveshaping circuit means comprising (a) a self-excited oscillator which is actuated in response to the direct current output from said power supply circuit means to oscillate, thereby generating a rectangular wave, and   (b) a waveform converting circuit means for converting said rectangular wave into a waveform which reaches a maximum level immediately after the current conduction has been started and decreases exponentially in time.     
     
     
       8. A device as set forth in claim 7 wherein said timer circuit means includes a timer variable means for adjusting a timer time; and said waveshaping circuit means includes an intermittent time variable means for adjusting an intermittent time of said intermittent direct current, and a load current variable means for adjusting the magnitude of said intermittent direct current flowing between said positive and negative terminals. 
     
     
       9. A device as set forth in claim 7 wherein said waveshaping circuit means includes light emitting display means which is turned on and off by said intermittent direct current, said light emitting display means being mounted on said positive terminal.